in this code:

#include <QApplication>
#include <QPushButton>

int main(int argc,char *argv[])
{
    QApplication app(argc,argv);
    QPushButton *button = new QPushButton("Button Text");
    QObject::connect(button,SIGNAL(clicked()),&app,SLOT(quit()));
    button->show();
    return app.exec();
}

intellisense is appearing when the cursor is in SIGNAL parenthesis to write button event. But it doesn't appear in SLOT parenthesis to write app method ?

is it related with & character in front of app ?